In the formation of FinFETs, a semiconductor substrate is typically etched first, resulting in recesses to be in the semiconductor substrate. The portions of the semiconductor substrate between the recesses are semiconductor strips. In order to reduce the pattern-loading effect, a plurality of dummy semiconductor strips is formed simultaneously as the formation of the semiconductor strips, on which FinFETs are to be formed. Residues of the dummy semiconductor strips are often left after the removal of the dummy semiconductor fins.